Conventional socks of this kind fall into two major categories:
socks with a covering into which the foot fits and comprising an opening for insertion of the foot, which is closed with a flap or tongue, and PA1 socks in which the foot-insertion covering uniformly encloses the foot and lower leg without breaks and, which, comprises at least one extensible area which becomes stretched when the foot is inserted into the sock, and then tightens around the lower leg of the skier. PA1 to allow the sock to be put on and taken off easily without requiring any manipulation by the skier as regards the insertion or covering of the foot, PA1 to provide for uniform covering of the foot and lower leg, without breaks, PA1 to guarantee the immobilization of the foot and/or lower leg in such a way as to complement the action produced by the boot-closure means, and PA1 to ensure the uniform quality of the firmness of the supports and of the comfort provided, regardless of the circumference of the skier's lower leg.
The first category of socks is disclosed, for example, of in FR 2,368,239 and EP 066,133. In FR 2,368,239, the foot-insertion opening is formed by slits laterally arranged along the area covering the lower leg of the skier. Thus, the sock incorporates a front portion covering the foot and the front of the lower leg, and a rear tongue-shaped portion covering the heel and the rear part of the lower leg. To facilitate insertion of the foot, the sock is, in the resting state, in open position. This structure has a first disadvantage resulting from the superposition of the edges of the sock covering in the area of the lateral slits. This disadvantage is amplified by the bevelled form imparted to these edges of the covering and by the arrangement of the pliable membranes which attach them. In fact, because of this arrangement, the least lateral sliding motion of the edges of the sock covering during skiing or when the sock is put on generates, laterally to their superposition, an interior fold which increases in size as the sliding motion becomes more pronounced, thus forming points of compression which are painful to the skier. A second problem arises from the fact that, in the resting state, sock is in the open position. In fact, as soon as the means used to tighten the upper have been released, the upper is forced to open completely under the effect of the force generated by the sock, which tends to return to its initial position. This arrangement thus requires, first, the use of closure elements to ensure that the foot will be covered when putting on the boot, and second, to provide elements or means for holding the upper of the boot in a relaxed position, i.e., not open, to allow walking, for example.
In EP 066 133, the sock comprises a covering fitting over the foot produced from a single piece, and an opening for insertion of the foot consisting of a single slit in the rear part of the sock, this slit being delimited by a pair of overlapping flaps. A closure system is combined with the flaps to ensure that the sock covers the foot and lower leg of the skier. Because of the superposition of the flaps, this sock has the same disadvantage as that of the sock according to FR 2,368,239, i.e., that slippage of the flaps occurring during skiing causes a change of position of the interior flap, or fold thus formed, in contact with the skier's leg and along the rear portion thereof. Another problem results from the use of the closure systems associated with the flaps. In fact, this system, which is accessible only when the boot upper is open, has the disadvantage of producing a sensation of immobilization of the lower leg which is unrelated to the system for closure of the boot upper. For example, the tightening of the sock may be relatively forceful and thus provide for close contact over the lower part of the leg, while closure of the boot upper may allow a certain degree of looseness to persist between the sock covering and the inner wall of the upper.
As regards the second category of socks, FR 2,360,271 and IT 1,117,339 disclose socks whose foot-insertion covering encloses the foot and lower leg of the skier uniformly and without breaks. As compared with the above-discussed socks, these socks have the advantage of incorporating no overlap or superposition of the configuration of the flaps and/or tongue.
FR 2,360,271 discloses an inner sock whose ascending upper section is closed over its entire circumference and has a higher degree of circumferential extensibility than do the other parts of the sock.
To this end, this wall is divided into strips which extend transversely to the circumference and which are contiguous in an alternating, accordion-like arrangement.
Accordingly, the sock may expand to allow the passage of the foot by unfolding the accordion-like strips resembling a kind of bellows.
Nevertheless, this design has a number of disadvantages, since stretching the strips causes the thickness of the sock wall to vary, and, moreover, imparts to the latter a flexibility which is not necessarily sought, in particular in the rear portion of the sock, which must form a solid support against the boot shell.
In addition, this unfolding of the strips produces an opposite effect, depending on the skier's body size. In fact, if the skier is big, he will tend to cause the strips to stretch markedly, and thus to decrease their strength, even though, in this case, this strength should be increased, and vice-versa. The quality of the support is thus directly influenced by differences in of the circumference of the skier's lower leg.
Moreover, this design entails the use of a material of the same kind. Experience has shown that a sock which is both comfortable and effective during skiing should give a relatively firm rear support and a front support under flection, depending on the degree of elasticity chosen as a function of the level of comfort desired.
In IT 1,117,339, the inner sock has with an ascending upper section closed over its entire circumference and with two lateral elastic zones intended to impart to it greater elasticity, in order to allow insertion of the foot. The upper section of the sock is provided with a rear and a front liner separated by the elastic zones. These liners are designed, to act as means for adjusting the fit of the sock between the inside surface of the boot shell and the skier's lower leg; and to act as support and comfort elements with respect to the lower leg. The result of this structure is that the stretching of the elastic zones does not modify the characteristics of the liners, and thus does not affect the quality of the front and rear supports. To the contrary, because the liners cannot be detached from the elastic zones, it is not possible to give greater importance to these elastic zones without doing so to the detriment of the surfaces of the liners, and thus, of the skier's comfort. Thus, whatever the solution chosen, the structure of such a sock can produce only a compromise between the sought-for ease of fitting the sock on the foot, which requires the substantial degree of extensibility and thus, of a large extensible surface are, and the comfort of the skier, which requires large support and covering surface areas. Moreover, because the front and rear liners are attached to the elastic zones, which, in use, necessarily undergo rapid wear and loosening, the relative position of these liners cannot remain stable during skiing and use over time, since there is an inherent weakening of the materials used to make these elastic zones.